Heat exchanger header construction



June 22, 1948- D. w. CHRISTENSEN HEAT EXCHANGER HEADER CONSTRUCTIONFiled Sept. 20, 1944 2 Sheets-Sheet 1 In, .9 f n ///l 5, a /P B u' fi am m 0 "Ila l;

Illlll Ill! June 22, 1948. cHRlsTENsEN 2,443,703

HEAT EXCHANGER HEADER CONSTRUCTION Filed Sept. 20, 1944 2 Sheets-Sheet 2Patented June 22 1948 HEAT EXCHANGER HEADER CONSTRUCTION Donald W.Christensen, Racine, Wis., assignor to Young Radiator Company, acorporation of Wisconsin Application September 20, 1944, Serial No.554,948

1 Claim. 1

Every type of gas-powered engine requires the use of a heat exchangeunit for dissipating the heat from the engine coolant. In automotiveequipment it is important to restrict the size and reduce the weightofheat exchange unit, as much as possible, so as to limit and lighten to aminimum the structure of the power unit employed in the transportationof persons and materials. The higher the capacity of such an engine themore expansive must be the heat exchange unit in order to effect therequired heat dispersion.

Withthe Diesel-type engine, the heat dispersion requirements .aremany-fold greater than with the other types of gas engines. Obviously,this calls for exceptionally expansive heat exchange units. When .theDiesel-type engine is employed as the power unit for railroadlocomotives heat exchange units of massive heat transfer area arerequired for the engine coolant in addition to that which may berequired for the lubricating oil. Accordingly, there has been presentedthe problem of providing a heat exchange unit, with adequate heattransfer area, sufficiently compact in form and light in weight to beconveniently arranged within the space available for such engineaccessories.

A factor which has had to be considered, and which particularly affectsthe structure of such units, is the excessive vibration created by highspeed travel, Moreover, the roof of a locomotive housing is regarded asthe most suitable place for .the heat exchange unit. This necessitatesproviding adequate heat transfer surface within a structure of long andnarrow proportions.

It has been found most practical to make up such a heat exchange unitfrom many separatelyassembled heat transfer sections, preferablyconstructed from light, fiat, thin, metal tubes through which the enginecoolant passes, and

which are finned and exposed to a transverse flow of heat-dispersingcooling medium. Obviously, the assembled sections require a massiveheader-tank wherewith to deliver and. discharge the engine coolant toand from these assembled heat transfer sections. Such header-tanks ofnecessity have to be quite long and of considerable capacity.

The main objects of this invention, therefore,

are to provide an improved form and method of constructing header-tanksfor large size, multisection heat exchange units; to provide animproved-form and method of constructing headertanks especially suitablefor use with heat exchange units required for Diesel, or similarhighpowered, motor equipment when employed for locomotives wherelightness, strength, and compactness, are simultaneous imperatives; toprovide an improved form and method of constructing header-tanks of thiskind comprising separately shaped, wrought metal forms secured togetherby the well-known hydrogen-brazing process; and to provide improvedheader-tanks of this kind which greatly economize the requirements formaterials and labor and results in a structure lighter in weight andgreater in rigidity than heretofore has been possible with other designsand methods of construction.

In the specific embodiment shown in the drawing:

Fig. -l is a perspective view of a pair of companion heat exchange unitsdesigned for use. in the roof of a Diesel-powered locomotive, themultiple heat transfer sections of each unit being supported in theirassembled relationship by and in communication with header-tanksconstructed in accordance with this invention;

Fig. 2 is-a plan view of one of the heat transfer sections, amultiplicity of which are required to make up one of the companionheatexchange units. A part of the figure is broken away so as to moreclearly indicate the internal construction of the finned, flat tubesthrough which the engine coolant flows;

Fig. 3 is an elevation of the structure shown in Fig. 2, various partsof the view likewise being shown in cross-section so as to more clearlyillustrate the internal structure of the headers and the finned tubes;

Fig. 4 is a fragmentary perspective view of the two separately shapedelements which go to make up-the header tank, the parts being shown inspaced relationship prior to their being assembled for the brazingoperation;

Fig. 5 is a'view of these two elements in their assembled relationshipimmediately prior to the brazing of the elements in a hydrogen-brazingfurnace; and

Fig. 6 is a fragmentary end view of the brazed header-tank in itscompleted form, preparatory to attachment to a bank of heat transfersections.

A heat exchange unit, employing header-tanks constructed in accordancewith this invention, comprises a plurality of heat transfer sections 1supported side by side on a pair of the improved header-tanks 8 and 9.The sections I are bolted to the header-tanks, by which they aresupported, and each section I communicates with its supportingheader-tank. When used for a Dieselpowered locomotive two of theseunits, each made up of eighteen of the sections I and a pair ofheader-tanks 8 and 9, are associated for mounting in the roof of thelocomotive, as shown in Fig. l.

The heat transfer sections 1 are of more or less conventional design.Each comprises a battery Ill of tubes and a pair of headers ii and I2.The tubes |3 are of the usual flat light metal form, supported at theirends in end plates l4 and I5. Closely spaced flns l5 are mounted on thetubes I3 between the end plates M and I5 and are capped on oppositesides by flanged side plates l1 and [8 which form a transverse passagefor a cooling medium, usually air, flowing between the fins I6 andaround the tubes IS.

The headers II and I2 are of identical construction, preferably being inthe form of castings. As clearly shown in Figs. 2 and 3, these headersfit within the tube supporting flange plates I4 and I5, thus providingcommunication between the headers and the engine coolant flowing throughthe tubes l3. Offsets or extensions l9 are formed on the headers II andI2, and their transverse ends 29 are provided with two sets of holes 2|and 22. The holes 2| provide communication with the interior of theheaders whereas the'holes 22 extend through bosses 23 to receive boltswhereby these sections are secured to the header-tanks 8 and 9, ashreinafter will more clearly'appear. As will be noted, the headers H andI2 are assembled with the battery ID of tubes so that the lateral endsare on opposite sides but have their outer faces 24 in parallel planes.These faces are machined so that, upon assembly with the tank headers 8and 9, a gasket may be used to form a watertight joint between theparts.

The provision of header-tanks, whereby to assemble and support aplurality of these heat exchange sections in a unitary structure withthe sections in communicating relationship with the header-tanks, suchas shown in Fig. 1, is the primary feature of this invention.

Making the header-tanks 8 and 9 as castings is out of the question. Thevibrations to which these header-tanks are subjected in normal use wouldrequire a weight for castings that would be prohibitive. Accordingly, ithas been necessary to devise a method of forming these headertanks fromtwo rolled wrought-metal elements subsequently brazing them together.The use of such elements of such length, formed from wrought metal, haspresented some difflcult problems both as to form and assembly.

Hydrogen brazing is a superior method of uniting two pieces of metal sofirmly that the joint is practically as strong as the two pieces ofmetal themselves. However, the temperature required for such" brazing isso high that the form and assembly of wrought metal elements has to besuch as to preclude against the possibility of warping or distortion ofthe elements when subjected to the intense temperatures; For that reasonthe form of these elements has had to be carefully designed to insureproper resistance to the strains and stresses met with in the welding oftwo such parts together, as well as strains and stresses to. which theheader-tanks are subjected in actual use. It is to that end that the twointerfltting parts are shaped with the arcuate portions with theparticular disposition of the flanges, as will be set forth presently.

The specific embodiment of the header-tank shown in the drawings,employs a pair of rolled, wrought-metal elongated elements 25 and 26.

Each element in transverse cross section is formed with an arcuateportion intermediate extensions and flanges, so that two'of the elementsmay be assembled with the arcuate portions and extensions in opposedspaced relationship with the flanges abutting face to face along whichportions the two elements are brazed together whereby the extensionsserve to appropriately space the arcuate sections apart so as to providean open-ended conduit extending the length of the assembled elements.

In the forming of element 25, the arcuate portion 2'! is of nearlysemi-circular form and has a tangential extension 28 formed along oneedge of the arcuate portion and an angularly disposed extension 29,formed along the other edge. These extensions terminate in flanges 30and 3|, respectively. The extension 29 is positioned at exactly a angleto the flange 30. Between extension 29 and the flange 3| there is anangular offset 32 which serves to space the flange 3| inwardly from theextension 29 and thus provides for a spacing apart of the extension 29from the corresponding extension on the other element. A series of holes33 are formed in the extension 29 throughout the length of the element.

The element 26 likewise has an arcuate section 34, but of materiallyless circumferential length than the arcuate section 27 of the element25. A flange 35 is formed along one longitudinal edge of the arcuatesection 34; along the other edge is formed on extension 36 disposed atright angles to the flanges 35 and terminating in flange 31. Holes 38are likewise formed throughout the length of the extension 36,positioned so as to register with the holes 33 when the parts areassembled. In this case, however, the holes 38 are counter-bored fromthe inside so as to form a shoulder 39 in connection with each of theholes 38. Flanges 3| and 31 are slightly offset from the planes of theextensions 29 and 36. This is made necessary so as to space the flangesslightly away from the adjacent edges 49 of the headers H and I2 whenthey are attached to the tank headers 8 and 9. Also the flange 38 isslightly offset from alinement with the extension 28.

The two elements, 25 and 26, are assembled with the flanges 39 and 35and the flanges 3| and 31 abutting face to face (as shown in Figs. 5 and6) with the arcuate sections 2! and 34 and the extensions 29 and 36opposed and spaced apart so as to form an open-end conduit extendingthroughout the length of the assembled elements.

With the two elements thus assembled and placed in the position shown inFig. 5, sleeves or bushings 4| are press-fitted into the holes 33 and 38and set against the shoulders 39, with the inner diameter of the sleeves4| in registration with the holes 38 in the extension 36.

With the two elements 25 and 26 temporarily clamped in their assembledpositions by any suitable means, and the bushings 4| pressed into place,the header-tank is ready for brazing. Prior to the brazing operationrods of copper 42 and 43 (see Fig. 5) are placed inside the assembledelements along the junctures of the flanges 3|] and 35, and 3| and 31,respectively. Likewise, rings of copper 44 and 45 are placed around thebushings 4|, directly above their juncture with the respectiveextensions 29 and 36. Such placing of copper rods and rings is a featurein the well-known hydrogen-brazing process whereby two metals subjectedto an intensive heat are firmly welded, or brazed, together.

In a hydrogen-brazing furnace for this purpose, the temperatureapproximates 2050 F.

Obviously this brings the metal to an almost white heat and the copperrods and rings melt and run in between the contiguous joints, forming afilm throughout the length of the joint which binds the contactingmetals so firmly together that it would require as much force to breakthe joint as would be required to sever the metal itself. The nature ofthis film is suggested'by the lines 46 and the shading 41, in Fig. 6.

Because of this intensive heat: the cross-sectional contour of theelements-the relative arrangement of the arcuate portions and theangular positioning of the extensions and flangeshas had to be designedso that there will be no sagging or collapsing of any portion of theelements during the brazing operation. Accordingly, the cross-sectionaldesign has then developed so as to resist the contemplated forcestending to warp or distort these elements when subjected to the brazingfurnace temperature with the parts assembled as shown in Fig. 5.

With the parts thus assembled, a header-tank is placed in thehydrogen-brazing furnace. Beir'ig of such a great length, and it beingimperative to heat the entire header-tank to the desired temperatureuniformly throughout its length in order to avoid any possibility ofwarping, it is necessary to have a hydrogen-brazing furnace of a sizesufllcient to accommodate the full length of one of these header-tanks.For the same reason it is necessary to have a cooling chamber of alength sufiicient to accommodate one of these header-tanks allowing itto cool uniformly throughout its length to avoid the possibility ofwarping.

After the header unit has become cooled, following the brazing process,holes 48 are drilled in the extension 29 in between the holes 33. Theholes 46 are positioned to register with the holes 2i in the headers IIand I! for the heat transfer sections 1. v

One end of each header tank has a cap 49 welded thereto so as tocompletely close one end, and the other end has a fitting 50 weldedthereto so as to provide for a connection with the source of supply ofthe engine coolant.

A header-tank so constructed is ready for as- .sembly with a pluralityof heat transfer sections 1, to constitute a complete heat exchange unitas rivets 5|, preferably the former, extending through the registeringholes 22, of the heat transfer section headers II and I2, and thebushings 4| of theheader-tanks 8 and 9. Obviously, a gasket would be'inserted between the extension 36 and the abutting headers of the heattransfer sections 1 so as to form fluid-tight joints around theregistering holes 2| and 48 of the heat transfer section headers II andI2, and the header-tanks 8 and 9. respectively.

Variations and modifications in the details of the structure andarrangements of the parts of this invention may be resorted to withoutdeparting from the spirit and coverage of the appended Number shown inFig. 1. As will be more or less evident claim.

I claim:

An article of manufacture of the class described comprising, a pair ofseparately-rolled wroughtmetal elements each of a straight length manytimes its width, one of said elements in transverse cross-section beingformed with an arcuateshaped portion intermediate lateral flangedextensions. one of which extensions is disposed approximatelytangentially with respect to said arcuateeshaped portion and the otherof which extensions is L-shaped with the two parts thereof respectivelydisposed transversely to and in the same general direction as said oneextension, the other said element in transverse cross-section beingformed with an arcuate-shaped portion intermediate a lateral flange anda lateral flanged extension, said elements being assembled with thefaces of said flanges abutting and the extension on said other elementdirectly opposed to said L-shaped extension on said one element wherebysaid arcuate-shaped portions are supported in opposed spacedrelationship to form a conduit the length of said elements, saidelements being hydrogen-brazed along said abutting flange faces, endclosures for said assembled elements, and a series of bushingsinterposed between registering apertures in and hydrogenbrazed to saidabove-mentioned opposed extensions, one of said elements having portscommunicating with said conduit.

DONALD W. CHRISTENSEN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date Plecker Jan. 29, 1907 Carrier Feb. '21,1933 Money Apr. 4, 1939 Saunders Nov. 14, 1939 Young Jan. 21, 1941Davies Oct. 28, 1941 842,580 1 398,713 2,152,312 2,179,702 2,229,2662,2co,7p4

